The present, disclosure relates to an image forming apparatus including a demountable developing device, such as a copy machine, a facsimile, a printer, or the like and relates particularly to a connection structure between a developing device and a developer supply mechanism, that supplies a developer to the developing device.
Conventionally, for the sake of easy maintenance, a developing device incorporated in an image forming apparatus is tilled beforehand with a given amount of developer (toner) and upon running out of the developer, is replaced as a whole with a new one. Front the economical viewpoint, however, such replacement cannot be performed frequently, and hence, forming a somewhat large number of sheets of images necessarily requires an increase in developer capacity, rendering it difficult to achieve miniaturisation of a developing device of the above-described type. In order, therefore, to achieve miniaturization, of a developing device, there has been proposed a developing device of a type to which a developer is supplied from a developer supply mechanism such as a toner storage container, an intermediate hopper, or the like, which is provided independently of the developing device.
Furthermore, with respect to a ease where, due to a restriction on a layout inside ah image forming apparatus, a developer supply mechanism and a developing device cannot be disposed adjacently to each other, there has been known a configuration in which a flexible developer supply passage such as a toner feeding tube, a conveying pipe, or the like is provided to establish communication between a developer supply mechanism, and a developing device.
By the way, in the above-described image forming apparatus, in order to simplify replacement and maintenance of the developing device, preferably, only the developing device can be demounted, with the developer supply mechanism left mounted on a main body side of the image forming apparatus.
The configuration including the flexible developer supply passage such as a toner feeding tube, a conveying pipe, or the like, however, presents a problem that the flexible developer supply passage is flexibly connected to the developer supply mechanism and to the developing device, which results in poor connection, strength between the developer supply passage aid the developer supply mechanism or the developing device. Furthermore, in a case of a configuration in which a plug provided at a tip end of a toner feeding tube is connected to a swingable shaft of a developing unit every time the developing unit is mounted/demounted it is necessary that the plug be connected or disconnected, rendering an operation of mounting/demounting the developing unit complicated.
Moreover, in mounting/demounting the developing device in/from a main body of the image forming apparatus, in order to avoid interference between a developing roller (developer bearing member) and a photosensitive drum (image bearing member), if is necessary that the developing device be mounted/demounted in a slate where it has been moved to a position where the developing roller is separated by a prescribed distance from the photosensitive drum. When the developing device is at an operation position thereof, however, if there is a variation in positional relationship between the developing roller and the photosensitive drum an image failure might occur, furthermore, in moving the developing device, if a connection portion of the developer supply mechanism, which is connected to a developer supply port of the developing device, is fixed to the main body side of the image farming apparatus, moving the developing device might cause a deviation in positional relationship between, the connection portion and the developer supply port of the developing device, leading to a possibility that a connection failure occurs between the developing device and the developer supply mechanism or that, due to irregular rotation of the developing roller, there occurs a variation in positional relationship between the developing roller and the photosensitive drum.
Furthermore, even in a case where no such connection failure occurs, if an opening portion of the developer supply mechanism is being left opened at the time of mounting/demounting the developing device, there is a possibility dial a developer adhering to the opening portion drops into the main body of the image forming apparatus, causing contamination inside the apparatus.